Vito, Gennaro F., author
Buku Teks
Barnes, Harry Elmer, author
Prentice Hall of India, 1966
Buku Teks
Adler, Freda, author
Houghton Mifflin, 1979
Buku Teks
Mannheim, Hermann, author
Routledge & Kegan Paul, 1970
Buku Teks
Hood, Roger G., author
McGraw-Hill, 1971
Buku Teks